chapter 14 - light Flashcards
state the 2 laws of reflection
the incident ray, reflected ray and the normal at the point of incidence lie in the same plane
the angle of incidence is equal to the angle of incidence
define refraction
the bending of light as it passes from one optical medium to another
define refractive index of a medium
ratio of the speed of light in vacuum to the speed of light in the medium
define critical angle
the angle of incidence in an optically denser medium for which the angle of refraction in the less dense medium is 90°
state the 2 conditions for total internal reflection to occur
light ray is travelling from optically denser medium to a less dense medium
angle of incidence in the optically denser medium is larger than the critical angle of the optically denser medium
state 3 characteristics of a mirror image
virtual
laterally inverted
upright
same size as object
equally far from mirror
state the 2 laws of refraction
the incident ray, refracted ray and the normal at the point of incidence all lie in the same plane
for two given media, the ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant, that is, sin i/sin r = constant
2 formulas for calculating refractive index
n = c/v
c = speed of light in a vacuum
v = speed of light in the medium
n = sin i/sin r
i - angle of incidence in a vacuum
r - angle of refraction in the medium
define total internal reflection
it is the complete reflection of a light ray in an optically denser medium at the boundary with an optically less dense medium
application of total internal reflection
glass prisms in binoculars
optical fibres
characteristics of optical fibres
thin and flexible
state what optical fibres be used for
they are used in telecommunications and medicine
advantages of using optical fibres over copper wires in telecommunication
optical fibres can carry much more information over longer distances than copper wires
optical fibres are lighter than copper wires
optical fibres will have a clearer signal due to less interference from external electric or magnetic fields
advantages of using optical fibres in medicine
optical fibres are thin and light - endoscopes and laparoscopes are kept small for minimally invasive examination/surgery
optical fibres are flexible - endoscopes and laparoscopes can curve around obstacles when taking images inside the body
how can optical fibres can be used in an endoscope
optical fibres are ideal to be used in the endoscope to transmit light for illumination and to capture the images inside organs
